Heart rate variability (HRV) can provide insights into the autonomic nervous system's function and balance, which is important for maintaining cardiovascular health and overall well-being. Here are some of the things that HRV can tell you:

Autonomic balance: HRV reflects the balance between the sympathetic and parasympathetic nervous systems. Higher HRV is associated with greater parasympathetic activity and a better balance between the two systems, while lower HRV is associated with greater sympathetic activity and an imbalance. This information can help assess the overall health of the autonomic nervous system.

Stress levels: HRV is inversely correlated with stress levels. Higher HRV is associated with lower stress levels, while lower HRV is associated with higher stress levels. This information can be useful in assessing an individual's stress levels and in developing strategies for stress management.

Exercise capacity: HRV can be used to assess an individual's exercise capacity. Higher HRV at rest is generally associated with better exercise capacity, and HRV can also be measured during exercise to assess cardiovascular fitness.

Risk of cardiovascular disease: Lower HRV has been associated with an increased risk of cardiovascular disease, including coronary artery disease, heart failure, and arrhythmias. HRV can be used as a predictor of future cardiovascular events.

Response to therapy: HRV can be used to assess the effectiveness of therapies for various conditions, such as hypertension, heart failure, and depression. Changes in HRV can indicate whether a therapy is working or not.

Overall, HRV can provide valuable information about an individual's autonomic function, stress levels, cardiovascular health, and response to therapy. It is a non-invasive and easily measurable parameter that can be used in a variety of clinical and research settings

Heart rate variability (HRV) norms can vary by age, sex, and other individual factors. HRV tends to decline with age, and there are also some sex differences in HRV. However, it's important to note that HRV norms can vary depending on the method of analysis and the specific HRV measures used. Here are some general trends in HRV by age and sex:

1. Age: HRV tends to decline with age, particularly after middle age. This is likely due to changes in the autonomic nervous system and other factors related to aging.

2. Sex: There are some sex differences in HRV, with women generally having higher HRV than men. This difference is thought to be related to hormonal factors, as well as differences in heart size and structure.

3. Other factors: HRV can also be influenced by other individual factors, such as physical fitness, stress levels, and health conditions

Resting heart rate (RHR) is the number of times your heart beats per minute while you are at rest, sitting or lying down, and not engaged in any physical activity or mental stress. It is a measure of the baseline rate at which your heart pumps blood throughout your body to supply oxygen and nutrients to your organs and tissues.

Typically, a healthy adult's resting heart rate ranges from 60 to 100 beats per minute, but the average resting heart rate is around 60 to 80 beats per minute. Athletes and highly fit individuals may have a lower resting heart rate, sometimes as low as 40 beats per minute, because their hearts are more efficient at pumping blood.

Measuring your resting heart rate can be a useful indicator of your overall cardiovascular health. An elevated resting heart rate can be a sign of underlying health conditions or risk factors, such as high blood pressure, obesity, or stress. Conversely, a lower resting heart rate can be a sign of good cardiovascular health and fitness.

Heart rate recovery (HRR) refers to the rate at which your heart rate returns to its normal or resting rate after exercise or physical activity. It is a measure of how quickly your cardiovascular system recovers from exertion.

During exercise, your heart rate increases to meet the demands of your body for more oxygen and nutrients. After you stop exercising, your heart rate gradually decreases as your body returns to its resting state. Heart rate recovery measures how quickly your heart rate drops during the first few minutes after exercise.

A faster heart rate recovery is generally considered a good indicator of good cardiovascular health. It suggests that your heart is able to quickly adapt to changes in activity levels and recover from physical stress. On the other hand, a slower heart rate recovery may indicate a higher risk of heart disease or other cardiovascular problems.

Heart rate recovery can be calculated by subtracting your heart rate at a specific time (e.g., 1 minute or 2 minutes) after exercise from your peak heart rate during exercise. The faster your heart rate drops, the higher your HRR score.

Respiration rate values measured by wearable electronics can provide insights into a person's respiratory health and activity levels.

Respiration rate is the number of breaths a person takes per minute, and it is an important vital sign that can help healthcare professionals monitor a person's health status. Wearable electronics, such as smartwatches and fitness trackers, can measure respiration rate through various sensors such as photoplethysmography (PPG) or accelerometers.

By monitoring respiration rate, wearable electronics can provide data on a person's breathing patterns, which can indicate changes in their respiratory health. For example, if a person's respiration rate is consistently high, it may indicate that they are experiencing shortness of breath or a respiratory condition such as asthma.

Additionally, respiration rate can provide insights into a person's physical activity levels. During exercise, the body's oxygen demand increases, and the respiration rate typically rises to meet this demand. By measuring respiration rate during exercise, wearable electronics can provide data on a person's exertion levels and help them monitor their workout intensity.

Overall, respiration rate values measured by wearable electronics can provide valuable information for both healthcare professionals and individuals looking to monitor their respiratory health and physical activity levels.

When a person experiences stress, their respiration rate typically increases as part of the body's fight or flight response. This response is a natural physiological reaction that prepares the body to respond to a perceived threat, whether it's physical or psychological.

When the body perceives a threat, the sympathetic nervous system is activated, which triggers the release of hormones such as adrenaline and cortisol. These hormones cause an increase in heart rate, blood pressure, and respiration rate, which prepares the body to take action.

Wearable electronics can measure changes in respiration rate and use this data to provide insights into a person's stress levels. For example, if a person's respiration rate is consistently high, it may indicate that they are experiencing chronic stress, which can have negative effects on their physical and mental health.

In some cases, when a person is intensely focused on a task, their respiration rate may decrease as their body enters a state of relaxation. This is because focusing on a task can help to shift attention away from stressors and reduce anxiety. In this state, a person's respiration rate may become slower and more regular, which can help to calm the body and reduce stress.

However, in other cases, when a person is intensely focused on a task that is stressful, their respiration rate may increase as their body enters a state of fight or flight response. This can happen if the task is perceived as a threat, and the body prepares to respond by increasing respiration rate, heart rate, and other physiological responses.

It's worth noting that stress can affect people in different ways, and the relationship between respiration rate and stress is complex. While some people may experience a decrease in respiration rate when they're focused on a task, others may experience an increase. Therefore, it's important to take into account individual differences and context when interpreting respiration rate data in relation to stress.

Measuring respiration volume can provide valuable information about a person's respiratory function, and it is commonly used in medical and research settings to assess lung health and diagnose respiratory conditions.

Respiration volume is a measure of the amount of air a person inhales and exhales during breathing. The volume of air can be measured directly using a spirometer or indirectly using wearable electronics such as smartwatches or fitness trackers that use accelerometers or other sensors to estimate respiration volume.

By measuring respiration volume, healthcare professionals can assess lung function and diagnose respiratory conditions such as asthma, chronic obstructive pulmonary disease (COPD), and pulmonary fibrosis. Respiration volume can also be used to monitor the progress of respiratory treatments and assess a person's response to therapy.

In addition, respiration volume can be used to monitor a person's physical activity levels. During exercise, the body's oxygen demand increases, and the respiration volume typically increases to meet this demand. By measuring respiration volume during exercise, wearable electronics can provide data on a person's exertion levels and help them monitor their workout intensity.

Overall, measuring respiration volume can provide valuable information for healthcare professionals and individuals looking to monitor their respiratory health and physical activity levels.

Yes, breathing exercises practiced in yoga, also known as pranayama, can help relieve stress and promote relaxation. Here are a few reasons why:

1. Activates the parasympathetic nervous system: The deep breathing techniques used in yoga activate the parasympathetic nervous system, which is responsible for the "rest and digest" response. This can help counteract the effects of stress on the body, such as increased heart rate and blood pressure.

2. Increases oxygenation: Breathing exercises in yoga can increase the amount of oxygen delivered to the body, which can help improve circulation and reduce muscle tension.

3. Reduces anxiety: Practicing deep breathing exercises in yoga can help reduce anxiety and promote a sense of calm. By focusing on the breath, the mind is diverted from stressful thoughts and can help reduce mental tension.

4. Improves mental focus: By focusing on the breath, breathing exercises in yoga can help improve mental focus and concentration, which can be helpful in reducing stress and improving overall well-being.

Overall, the deep breathing techniques practiced in yoga can be a helpful tool in managing stress and promoting relaxation. However, it is important to note that yoga should not be used as a substitute for professional medical advice or treatment

Slouching can have a negative impact on a person's health in several ways:

1. Musculoskeletal problems: Slouching can cause strain on the muscles and ligaments in the neck, back, and shoulders, leading to pain and discomfort. Over time, this can lead to chronic musculoskeletal problems such as neck and back pain, muscle stiffness, and reduced range of motion.

2. Digestive issues: Slouching can also compress the organs in the abdomen, leading to digestive issues such as acid reflux and constipation.

3. Breathing difficulties: Slouching can restrict the movement of the rib cage, making it harder to take deep breaths and reducing lung capacity.

4. Headaches: Poor posture, especially when using electronic devices, can lead to tension headaches due to strain on the neck and shoulders.

5. Fatigue: Slouching can reduce blood flow and oxygen to the brain, leading to fatigue and decreased mental alertness.

6. Poor mood: Slouching can also affect a person's psychological well-being, leading to feelings of sadness, stress, and anxiety.

Overall, slouching can have a negative impact on a person's physical and mental health. By practicing good posture, people can reduce the risk of these negative health outcomes and improve their overall well-being.

Sleep is essential for a person's health and well-being in a variety of ways. Here are some of the reasons why sleep is so important:

1. Physical health: Sleep plays a crucial role in physical health by allowing the body to repair and regenerate cells and tissues, strengthen the immune system, and regulate hormones that control appetite and metabolism. Adequate sleep is also associated with a lower risk of developing chronic health conditions such as obesity, diabetes, cardiovascular disease, and certain types of cancer.

2. Mental health: Sleep is important for mental health, as it plays a role in regulating mood, reducing stress, and improving cognitive function. Adequate sleep can also help prevent mental health conditions such as depression, anxiety, and bipolar disorder.

3. Memory and learning: Sleep is important for memory consolidation, which is the process by which the brain stores and integrates new information. Getting enough sleep can help improve learning and memory retention.

4. Athletic performance: Sleep is important for athletic performance, as it helps the body recover and repair from physical activity, reduces inflammation, and improves reaction time and accuracy.

5. Safety: Sleep is important for safety, as sleep deprivation can impair judgement, reaction time, and decision-making, increasing the risk of accidents and injuries.

Overall, getting enough sleep is crucial for maintaining good physical and mental health, improving cognitive function, and promoting overall well-being. Adults should aim to get 7-9 hours of sleep per night, while children and teenagers need even more.

Smart wearables, such as fitness trackers and smartwatches, use a variety of sensors and algorithms to measure sleep. Here are some of the common methods used:

1. Accelerometers: Many smart wearables have built-in accelerometers that can detect movement and changes in position. By analyzing the patterns of movement during the night, the device can estimate when the wearer is asleep and when they are awake.

2. Heart rate monitors: Some smart wearables also have heart rate monitors that can detect changes in heart rate during the night. By analyzing heart rate variability, the device can estimate different stages of sleep, such as deep sleep and REM sleep.

3. Environmental sensors: Some smart wearables also have environmental sensors, such as temperature and light sensors, that can detect changes in the sleep environment. By analyzing these changes, the device can estimate when the wearer is asleep and when they are awake.

4. Algorithms: Smart wearables use complex algorithms to analyze the data from the sensors and provide an estimate of sleep quality. These algorithms take into account factors such as movement, heart rate, and environmental changes to determine the different stages of sleep and calculate a sleep score.

Overall, smart wearables use a combination of sensors and algorithms to estimate sleep quality. While these devices may not be as accurate as a professional sleep study, they can provide useful insights into sleep patterns and help users identify ways to improve their sleep habits.

People who have obesity are at increased risk for many diseases and health conditions, including the following:

• All-causes of death (mortality)

• High blood pressure (hypertension)

• High LDL cholesterol, low HDL cholesterol, or high levels of triglycerides (dyslipidemia)

• Type 2 diabetes

• Coronary heart disease

• Stroke

• Gallbladder disease

• Osteoarthritis (a breakdown of cartilage and bone within a joint)

• Sleep apnea and breathing problems

• Chronic inflammation and increased oxidative stress

• Some cancers (endometrial, breast, colon, kidney, gallbladder, and liver)

• Low quality of life

• Mental illness such as clinical depression, anxiety, and other mental disorders

• Body pain and difficulty with physical functioning

Obesity is associated with various health problems, such as diabetes, cardiovascular diseases (CVDs), depression, some forms of cancer, sleep apnea, osteoarthritis, among others. The body mass index (BMI) is one of the best known measures of obesity. The correlation between the BMI and body fatness is fairly strong but even if two people have the same BMI, their level of body fatness may differ.

In general: 

• At the same BMI, women tend to have more body fat than men.

• At the same BMI, the amount of body fat may be higher or lower depending on the racial/ethnic group.

• At the same BMI, older people, on average, tend to have more body fat than younger adults.

• At the same BMI, athletes have less body fat than do non-athletes.

The accuracy of BMI as an indicator of body fatness also appears to be higher in persons with higher levels of BMI and body fatness. While, a person with a very high BMI (e.g., 35 kg/m2) is very likely to have high body fat, a relatively high BMI can be the results of either high body fat or high lean body mass (muscle and bone). A trained healthcare provider should perform appropriate health assessments to evaluate an individual’s health status and risks.

Readings of BMI:

< 18.5 – Underweight

18.5 to 24.9 - Normal weight

25 to 29.9 – Overweight

> 29.9 Obese

For a better understanding, we have also converted the BMI to a scale of 1 to 10, one being bad to 10 being best

The waist-to-height ratio, calculated by dividing the waist circumference (WC) by height, has recently gained attention as an anthropometric index for central adiposity. It is an easy-to-use and less age-dependent index to identify individuals with increased cardiometabolic risk. Waist-to-height-ratio is equivalent to or slightly better than WC and superior to body mass index (BMI) in predicting higher cardiometabolic risk. In children and adolescents, studies have shown that the waist-to-height ratio is similar to both BMI and WC in identifying those at an increased cardiometabolic risk. Additional use of waist-to-height ratio with BMI or WC may be helpful because waist-to-height ratio considers both height and central obesity. Waist-to-height ratio may be preferred because of its simplicity and because it does not require sex- and age-dependent cutoffs; additionally, the simple message 'keep your WC to less than half your height' may be particularly useful.

A Body Shape Index (ABSI) is associated with total mortality and cardiovascular events.

A Body Shape Index (ABSI) is calculated by dividing waist circumference (WC) by its estimate obtained from allometric regression of weight and height. ABSI was designed to be minimally associated with weight, height and body mass index (BMI) so that it can be used together with BMI to disentangle the independent contribution of WC and BMI to cardio-metabolic outcomes ABSI also predicts incident cardiovascular disease (CVD) with an accuracy similar to that of common laboratory measurements. ABSI correlates only slightly with height, weight and BMI, indicating that it is independent of other anthropometric variables in predicting mortality. ABSI was positively associated with serum insulin and C-reactive protein. ABSI is positively associated with fat mass and negatively associated with fat-free mass.

ABSI is good to be at around 75

However, for ease of understanding, we have converted the ABSI to a scale of 1 to 10. One being bad to 10 being best.

By looking at various body shape measurements viz A Body Shape Index (ABSI), waist-to-height ratio and body mass index (BMI), some of get confused. For this matter we have combined the above three matrices and created an Overall Body Index to give a wholesome picture of the body. Again, for the ease of use and understanding, we have rated it from 1 to 10. One being the poor and 10 being the best. The detailed descriptions of the parameters can be read from the respective readings of the matrices.

There are two types of Respiration: Aerobic Respiration — Takes place in the presence of oxygen. Anaerobic Respiration –Takes place in the absence of oxygen.

When we exercise, our bodies require quite a lot of energy to fuel muscle contraction. We break down ATP (a high-energy compound), and a hydrogen ion is released in the process. During strenuous exercise where oxygen is limited, our metabolism can’t keep up with the ever-growing number of hydrogen ions in our body.

The level above which pyruvate—an intermediate product of anaerobic metabolism—is produced faster than it can be used aerobically; unused pyruvate splits into lactate (lactic acid) and positively charged hydrogen ions; continued exercise above the lactate, or anaerobic, threshold results in accumulation of these ions—acidosis—causing exhaustion and intramuscular pain

Lactic acid is more of a helper to our muscles since it ultimately provides energy. The lactic acid that is produced during glycolysis is easily disassociated, which means that once lactic acid leaves the muscle cell and enters the bloodstream the lactate and hydrogen ion are no longer attached and present as lactic acid, but they are both present separately in the body as lactate and a hydrogen ion. The lactate is often recycled and used as energy, which is much needed during bouts of intense exercise.

lactate doesn’t cause the acidic environment, it tries to minimize it. It’s when this buffering process can’t keep up that our muscles start to burn.

The lactate threshold is a point during exhaustive, all-out exercise at which lactate builds up in the bloodstream faster than the body can remove it. The only way to make up the difference is to rev up anaerobic glycolysis, which occurs in environments environment lacking oxygen.

During moderate exercise at a steady state, lactate can be absorbed quickly, but with high-intensity exercise, it is produced faster than the body can absorb it. Presumably, having a higher lactate threshold means an athlete can continue at a high-intensity effort with a longer time to exhaustion.

This lactate threshold is marked by a slight drop in pH (from 7.4 to about 7.2). This drop is thought to cause fatigue and reduce the power of muscle contractions which can lead to a reduction in performance. The highest workload that can be maintained without lactate continuously accumulating over time is called maximal lactate steady state (MLSS)

Lactate values differ for venous and arterial blood, and normal ranges vary among labs. Most labs define normal as 0.5 to 2.2 mmol/L for venous blood and 0.5 to 1.6 mmol/L for arterial blood. Lactate is measured in millimoles per litre of blood.

Lactate Threshold Values

Average person: 60% of VO2 max

Recreational athlete: 65% to 80% of VO2 max

Elite endurance athlete: 85% to 95% of VO2 max

Training

Lactate threshold training means increasing exercise intensity so you train at or just above your LT heart rate. This training can be interval training or steady-state training. A combination of interval, high-intensity training, and continuous steady-state training may work best. The duration of your exercise should be based on your current fitness level and goals. For example:

Interval LT training sample plan: Twice a week, perform three to five 10-minute high-effort intervals at 95% to 105% of your LT heart rate, with three minutes of rest between intervals.

Continuous LT training sample plan: Twice a week, perform one 20- to 30-minute workout at high-intensity effort (95% to 105% of your LT heart rate).

Increase your training volume by 10% to 20% each week to progress. Remember to track your progress and re-test every few months to see if your training efforts are working. If not, you might need to adjust by adding frequency, time, or intensity.

Recovery

Recovery is vital for optimal performance without overtraining. Rest days or days of light work should be interspersed between your active training days. Recovery work such as mobility, stretching, foam rolling, massage or other methods might boost recovery as well. Remember to get enough sleep each night, as that will play a critical role in your performance and recovery.

Maximum heart rate is the highest number of beats your heat can pump per minute when it's under high stress (physical or otherwise) during all-out strenuous exercise. Maximum heart rates can vary from person to person and they are not an indicator of physical fitness. In other words, it doesn't rise as you get stronger or faster, and it doesn't mean that someone with a higher HR_MAX is in better shape than you.

While most formulas calculate a ballpark HR_MAX based on your age and gender, it's actually more complicated than that. All of these factors can come into play in determining your HR_MAX:

• Age: Your HR_Max can decline as you age.

• Altitude: Altitude can lower your HR_Max.

• Fitness: HR_MAX has nothing to do with how physically fit you are.

• Genes: Your HR_MAX is influenced by your genes.1

• Individual differences: HR_Max can vary significantly even among people of the same age and sex.

• Size: HR_MAX is usually higher in smaller people, which is why women often have a higher HR_MAX than men.

• Working out: Training doesn't really change your HR_MAX, but if there is any change, it may get lower as your body experiences expanded blood and heart volumes.

Calculating max heart rate is necessary for heart rate training and understanding what your heart rate zones are. Once you know what your max HR is, you can then monitor your heart rate while exercising and track what percentage of your max you hit during certain workouts and activities.

• For vigorous-intensity physical activity, your target heart rate should be between 77% and 93% of your maximum heart rate.

• If you're very sedentary with no exercise at all, you should work at about 57% to 67% of your HR_MAX.

• If you engage in minimal activity, you should work at 64% to 74% of your HR_MAX.

• If you exercise sporadically, you should work at 74% to 84% of your HR_MAX.

• If you exercise regularly, you should work at 80% to 91% of your HR_MAX.

• If you exercise a lot at high intensities, you should work at 84% to 94% of your HR_MAX.

However, best athletes hit 100% of their HR max for a brief period during finish of an exercise event or short burst of energy consuming moments.

VO2 max is measured in milliliters of oxygen used in one minute per kilogram of body weight (mL/kg/min).

When you exercise, your heart and your lungs are working hard to pump oxygenated red blood cells around your body to the muscle tissue, where the oxygen is being used. The more oxygen your body can use, the more your muscles can work

VO2 max or maximal oxygen uptake or Cardio Fitness Score refers to the maximum amount of oxygen you can utilize during exercise. It's commonly used to test the aerobic endurance or cardiovascular fitness of athletes before and at the end of a training cycle.

To measure VO2 max, you wear a mask and heart rate monitor hooked up to a treadmill or stationary bike. The mask is connected to a machine that collects and measures the volume of oxygen you inhale, and the amount of air you exhale.

You'll slowly increase exercise intensity on the treadmill or bike — getting faster and/or adding more resistance — until your oxygen consumption remains steady despite an increase in intensity.

Once you reach that plateau, your body moves from aerobic metabolism to anaerobic metabolism — that is, your body stops using oxygen to fuel the breakdown of carbohydrates, amino acids, and fats because there isn't enough oxygen there.

Shortly after you reach that switch, your potential workload plateaus and muscle fatigue sets in. You have to return to an aerobic state of movement to keep going

“We’re measuring the amount of oxygen that goes in at the mouth, and then the amount of oxygen that gets breathed out, and we’re looking at the volume of that gas that you’re using.

So from the 21% going in, the percentage coming out is usually somewhere between 16% and 19%.

It's not the same thing as heart rate, though it can be just as effective, if not more so, to measure and track your fitness progress.

VO2 isn't excess post-exercise oxygen consumption (EPOC), which refers to the increase in oxygen your body uses after a workout, not during.

But don't confuse VO2 max with the lactate threshold, the point during exercise where lactate builds up in your bloodstream faster than your body can expel it.

When you reach your lactate threshold, you get that familiar burning or cramping feeling. You reach your lactate threshold at about 50 to 80% of your VO2 max.

If the number increases then it means your training is effective

Improving the VO2 Max means you develop better endurance

The more oxygen your body can use, the more your muscles can work

Like heart rate, there's no one "good" VO2 max. Your VO2 max will differ from someone else's based on age, gender, fitness level and outside factors like altitude.

The average sedentary (inactive) male achieves a VO2 max of about 35 to 40 mL/kg/min, and the average sedentary female scores approximately 27 to 30 mL/kg/min.

Elite male runners have shown VO2 maxes of up to 85 mL/kg/min, and elite female runners have scored up to 77 mL/kg/min.

A good VO2 max for a 25-year-old male is 42.5-46.4 mL/kg/min, while a good value for a 25-year-old female is 33.0-36.9 mL/kg/min.

Vo2 Max scores can vary based on a number of factors in addition to fitness, such as your gender, age and genetics, but a vo2 max measurement for an average person in their mid 30s to mid 40s is likely to be around:

Women – 31 ml oxygen/kg of body weight/minute

Men - 42 ml oxygen/kg of body weight/minute

This means: an average woman (35-45 years old) consumes about 31 ml of oxygen for every kg that she weighed during each minute of a run. And an average man (35-45 years old) consumes 42 ml of oxygen for every kg he weights during each minute of a run.

For a fit person in the same age range the Vo2 Max is likely to be around:

Women – 45+ ml oxygen/kg of body weight/minute

Men – 51+ ml oxygen/kg of body weight/minute

Age plays a central role with VO2 max scores typically peaking by age 20 and declining by nearly 30% by age 65. Usually it reduces 1% per year

Gender also contributes with elite female athletes typically having higher VO2 max values than their male counterparts. However, when values are adjusted based on body size, blood volume, and hemoglobin content, a man's VO2 max will generally be 20% higher than a woman's.

Altitude contributes simply because there is less air to consume at higher altitudes. As such, an athlete will generally have a 5% decrease in VO2 max results for every 5,000 feet gained in altitude.

Your Vo2 Max should naturally improve as you increase the distance and duration of your training sessions, but here are three additional activities you might want to consider to improve your Vo2 Max:

• Hill reps – hill sessions of 2-3 minutes are a great way to increase your Vo2 Max.  Start with 3 – 4 reps and build up to 8 – 10 reps.

• Interval training - Divide a 5k run into between 4 and 8 intervals where you push yourself, so that you are at your max heart rate at the end of the session.  Always remember to warm up and cool down properly when you are doing hill reps or interval training!

• HIIT training – a 15–30 second activity at maximum effort, repeated 10–20 times over a number of weeks is a really effective way of building your score. Joe Wicks has a great introduction to HIIT training.

• Other

https://www.fleetfeet.com/blog/boost-your-fitness-with-these-race-specific-vo2-max-workouts   

Example 1: 4 x 800m (or 4 x 3 minutes) @ VO2 max intensity (3:00 jog recovery after each interval)

Example 2: 5 x 1000m (or 5 x 4 minutes) @ 5K race pace effort (3:00-4:00 jog recovery after each interval)

Example 3: Ladder workout of 2000m @ 10K pace; 1600m @ 5K pace; 1200 @ VO2 max; 800 @ VO2 max (3:00-5:00 rest after each)

Example 4 (advanced): 3-mile tempo (4:00 jog); 4 x 1000 @ VO2 max (3:00 jog)

Example 5 (intermediate): 10 minutes @ tempo effort (3:00 jog); 4 x 3 minutes @ VO2 max effort (3:00 jog)

Example 6: 2 x 5 mins @ VO2 max (equal jog recovery), followed by 2 x 3 minutes (equal recovery) on runnable singletrack trail.

Example 7: 8-7-6-5-4-3-2-1 minute fartlek, starting at tempo effort and picking up to VO2 max effort for the last few minutes (half-time recovery for first five intervals, then equal time)

Example 8: 5 x uphill 800 @ VO2 max effort (3:00 recovery or jog to base of hill)

VO2-max workout: 6 x 800 metres at VO2-max pace with 4 to 6 minutes of recovery jogging between efforts. You should do VO2-max workouts no more than once a week

VO2 max for the 5k

12 x 400 meters at 1 mile to 3k race pace w/1:30-2:00 minutes rest

12 x 300 meters at 5k pace w/ 30-40 seconds rest

5 x 3 minutes hill repeats with jog down recovery

VO2 max for the 10k and half marathon

16 x 400 meters at 5k – 10k pace with every 4th 400 at 1 mile-3k pace w/ 60 seconds between reps

4 miles continuous tempo alternating 400m at 3k-5k pace and 1200 meters at Marathon pace

4 x 2 minutes Hills w/ jog down recovery, 1 mile on a flat surface at 10k pace, 4 x 2 minute Hills w/ jog down recovery

VO2 max for the Marathon

2 sets of 10 x 400 meters at 5k pace w/ 200 meters jog rest and 400 meters jog between each set

20 x 200 meters at Mile to 3km pace w/ 200 meters jog recovery

6 x 3 minutes at 3k to 5k pace w/ 3 minutes walk or jog between

Easy

Easy runs

Hard

Tempo runs

Hard

VO2-max runs

Hard

Speed-form runs

Hard

Yasso 800s

Easy

Long runs 

Most beginner and intermediate runners do just two hard days a week. More advanced runners can do three hard days if they're careful.

A hard session should usually be followed by one or (even better) two easy day sessions. Easy days can include rest days and cross-training days.

Most beginner and intermediate runners should run no more than 4 to 6 days a week. We recommend one or two rest days, when you do no training at all (or just take a relaxed 30-minute walk) and one or two cross-training days.

Yes, It can be estimated using different other techniques and a very practical estimate can be arrived at.